1. Field of the Invention
The present invention relates to a bumper on the draft links of a tractor three point hitch, and in particular to a wedge shaped bumper longitudinally adjustable along the draft link, the bumper having a contact surface with a curvature in the longitudinal direction of the draft link to compensate for different rotational positions of the draft link resulting from different positions of the bumper along the length of the draft link.
2. Description of the Related Art
A bumpers or pads for the draft links of three point hitches that are tapered lengthwise of the draft link are known, as shown in U.S. Pat. No. 4,470,613. There the pad is tapered lengthwise of the draft link and is adjustable in position lengthwise of the draft link to permit minor adjustment in the draft link end spacing and to compensate for wear in the co-action between the pad and the sway block mounted to the tractor frame. The pad surface is curved in a vertical plane but forms a flat surface in the lengthwise direction of the draft link. As the pad is moved lengthwise of the draft link, causing the draft link end spacing to change, the angular orientation of the draft link relative to the tractor longitudinal center changes, also changing the orientation of the bumper relative to the sway block and where the bumper contacts the sway block.
The present invention provides a bumper that is tapered, i.e. wedge shaped and movable lengthwise of the draft link. The tapered shape of the bumper enables the bumper, when it is moved longitudinally of the draft link, to change the end spacing of the draft links to adjust between the free link spacing for a hitch category and the appropriate quick coupler end spacing for the category. The bumper has a T-shaped slot extending lengthwise of the bumper from one end. The slot is open on the side of the bumper facing the draft link. The slot receives and retains the head of a mounting bolt that extends from the slot and through an aperture in the draft link to mount the bumper thereto. The slot enables the bumper to be longitudinally adjusted along the draft link.
The draft link has a longitudinally extending pocket with laterally projecting upper and lower walls. The upper and lower walls have diverging mounting faces for seating of the bumper thereon. The bumper, in turn, has complementary inclined mounting faces engaging the diverging mounting faces of the draft link walls. This provides greater vertical load carrying capability to the bumper than is available with flat, vertical, contact surfaces between the bumper and the draft link. With flat contact surfaces, the vertical loading on the bumper block is transmitted to the draft link by shear loading of the mounting bolt. This shear loading of the bolt is eliminated by the diverging mounting faces of the draft link and the complementary inclined faces of the bumper of the present invention.
To provide further adjustability and enable the draft link end spacing to be varied between wide and narrow hitch standards, or between two hitch categories, a spacer is available for placement between the draft link and the bumper. The spacer is of a uniform thickness along the entire length of the spacer and thereby does not add to or detract from the taper of the bumper. The spacer has one side with inclined mounting faces like the bumper and complementary to the diverging mounting faces of the draft link for engagement therewith. The opposite side of the spacer is formed with a longitudinally extending pocket, like the draft link, with upper and lower walls having diverging mounting faces for seating of the bumper thereon.
The bumper is formed with a longitudinally curved contact surface for engagement with the sway block carried by the PTO housing of the tractor. As the bumper is moved along the draft link, changing the draft link end spacing, the curvature of the bumper contact face compensates for the rotation of the draft link and maintains a constant angular relationship between the bumper contact face and the sway block as the bumper is adjusted longitudinally of the draft link and as the spacer is removed or added.